Elongated material in the present context may include ribbons, tapes, band-shaped material, for example, made of textiles, synthetic materials, or paper. The term also includes threads, yarns, ropes, strings, and the like. Such materials frequently require a treatment in a treatment chamber. For this purpose, the elongated materials must be transported through the treatment chamber passing through an inlet into the chamber and through an outlet out of the chamber. Inside the chamber or treatment zone the surface of the elongated material passes along the surface of at least one guide body which changes the travel direction of the elongated material through the treatment zone or chamber. The material to be treated usually travels through the treatment zone along a meandering path, for example, for the purpose of drying or dyeing or impregnating or the like. The conventional direction changing guide body is usually a rotatably mounted roller which is either positively driven or it rotates as a result of the contact of its surface with the material being treated.
In order to transport the material through the treatment chamber or zone, it was necessary heretofore, to provide a positive drive. Such positive drive may involve the driving of the guide rollers and/or a further drive which pulls the elongated material through the treatment chamber or zone. In all conventional transport drives of this type it is unavoidable that the elongated material is subjected to a substantial transporting strain caused by a longitudinally effected stress applied by the pulling force of a take-up reel or the like. The direction reversing guide rollers inside the treatment chamber are mounted in a fixed position, except one such roller is mounted in a floating manner to provide for some yielding, whereby the elongated material is protected to some extent against too large tension stress. Thus, when the take-up roller rotates too fast, the floating roller travels out of its original position into a position in which the total length of elongated material within the treatment zone or chamber is reduced. This movement direction of the floating roller is maintained, for example, until a predetermined threshold tensile stress is reached in response to which, for example, an end switch or sensor switch provides a signal for the control of the feed advance. Such a signal may slow down the take-up speed or may increase the feed-in speed. As a result, the floating roller again moves in the opposite direction until a respective threshold value is sensed. The feed advance is thus controlled to provide for a back and forth shuttling of the floating guide roller between presettable limit values for the tensile stress applied to the material.
In spite of such a floating guide roller it is unavoidable, that the type of material hereinvolved may be exposed to relatively large tension stress during its transport through a treatment zone or chamber. This is due to the fact that the material being transported must take up at least that stress that is necessary for moving the floating guide roller. To this stress is added a stress component necessary for rotating any guide rollers mounted in a stationary, but rotatable position. Even if the stationarily mounted guide rollers are positively driven, there may be synchronization errors that also result in undesirable tensions on the elongated material. Even the friction in the bearings of guide rollers that are rotating due to the contact with the elongated material results in undesirable tension stress which may differ from roller to roller and which adds up with the number of rollers. Exposing the elongated material to such tension stress is undesirable because it adversely influences the quality of the finished elongated material. This problem has not been solved heretofore.